1. Can I add a bash guard to an XT crankset, if I want to keep both chain rings? I dont want a chain device (I think…) hoping that the clutch mech will keep things in place.

2. I’m reusing my old XT 3×9 front mech, are there any advantages in getting a 2×10 front mech? Obviously I’ve adjusted the limiters so that my mech doesnt over shift (I was previously running a bash in any case).

1. Assuming you’ve got a standard ‘triple’ crankset then yes, it just fits in the normal ‘outer ring’ position. Otherwise, you’d have to get something like Hope’s new chainring with integrated bash ring I reckon.

2. I found that a double specific mech helped keep the chain on better. Most seem fine with a standard triple front mech though.

1. If you do go for the chain device then avoid the MRP 2x, it’s a complete bag of sh1te and made of sh1te stuff that can’t retain a chain. It’s also made and distributed by sh1sters who quite clearly have done sh1te all research. Go for the new E*Thirteen:

Skid Bash Version
Full Bash Version

There are 2 different versions one of which can be used with a full bash ring but I’ve got the skid version and it does a great job. Depending on how your front mech is set up the top fin will also help stop chain suck off the front.

2. I tried sticking with a 2×10 front mech which was for a 42T ring when I dropped down to a 39T and even with the chain device I found the chain would jump off the top ring to the bottom. The smaller front mech offers some retention and I haven’t had any issues yet

I find that 2×10 FDs seem tighter on tolerance of size of big ring. I’m currently using a Shimano rated for 38 or 42t on a 36/24 and occasionally get chain jam but usually with other factors contributing like a frozen chain.
Proper 2×10 as opposed to double and bash type chain sets have the centres of the rings placed differently which is where some of the less-cross-chain advantage comes from. A triple set up as double and bash is s backward step in this respect.
Real 2x FDs have shorter cages than triples which helps alleviate rub and possible mis shift caused by rub if there’s enough slack.
Clutches are awesome.
Chain device is something I’m trying to avoid as I don’t want extra idlers if I can avoid them!
I plan to switch my old double and bash for a newer real 2x crank at some point so I’m not messing with the FD. I’m constrained by needing an E2 for my frame…